Field of the Invention
The present invention relates to an imaging apparatus, an imaging system, and an image processing method.
Description of the Related Art
In a solid-state imaging apparatus of a single-plate type, in order to obtain a color image, color filters (CFs) each configured to transmit light of a specific wavelength component, for example, light of a color of red (R), green (G), or blue (B), are arrayed in a predetermined pattern. As a pattern of CFs, a pattern having a so-called Bayer array is often used. In the following, a pixel in which the CF of R is arranged is referred to as “R pixel”, a pixel in which the CF of G is arranged is referred to as “G pixel”, a pixel in which the CF of B is arranged referred to as “B pixel”, and a pixel in which no CF is arranged is referred to as “W pixel (white pixel or clear pixel)”. In addition, the R pixel, the G pixel, and the B pixel are sometimes referred to collectively as “RGB pixels” or “color pixels”.
In order to improve the sensitivity of the solid-state imaging apparatus, there is proposed a configuration for increasing the proportion of pixels from which information on a luminance is obtained easily. Above all, the W pixel that widely transmits light within a visible light range enables to improve the sensitivity and to obtain an image having a high S/N ratio. International Publication No. WO2010/090025A describes an imaging apparatus configured such that a ratio of the numbers of RGB pixels and W pixels is R:G:B:W=1:1:1:1. This imaging apparatus restores an RGB image for each frame time based on motion information, which has been detected from an image of W pixels, and images of RGB and an image of W pixels, which have been subjected to addition for each frame.
The apparatus described in the international publication No. WO2010/090025A is directed to reduce color noise by increasing the number of frames of RGB pixels to be subjected to the addition. However, there is a problem in that a color afterimage is caused by an object exhibiting a large motion.